Fuse plug



Sept. 23, 1930. LUDMG I 1,776,685

FUSE PLUG Filed July 25, 1929 Elwventoz L au/s 1- udvw q Patented Sept.23, 1930 UNITED STATES PATENT OFFICE FUSE Application filed July 25,

My invention relates to'fuse plugs of the type having an opening coveredwith transparent material through which the interior of the plug may beobserved. It has for its 6 main object to provide an ordinary fuse plugwith means which will positively indicate drawing of a preferredembodiment, but it will be understood that certain modifications mightbe made without departing from the scope of the invention; in thedrawings Fig. 1 is a cross-sectional front view of a fuse plugcontaining my invention,

Fig. 2 is a cross-sectional side View, and

Fig. 3 is a top view.

Referring now to all the views, 1 is the ordinary porcelain body of afuse plug, 2 the threaded metal ferrule, 3 the cap, 4 the opening in thecap through which the interior recess 5 of the body may be observed, and6 the transparent mica disc usually covering this opening.

My invention consists in forming two diametrically opposite seats 7 and8 in the top of the body member, to place a thin rod 9 in these seats sothat it is suspended over the recess 5, and to pass the fusible metalstrip 10 over the rod so that both will be located immediately under themica disc 6. The ends of the fusible metal strip are soldered to theeyelet 11 and to the ferrule 2 in the usual manner. I prefer to decreasethe width of the metal strip where it passes over the rod, as shown at12, so as to cause the metal to fuse at this point.

It will readily be seen that with the fusible metal right against themica disc it is easy to observe when the fuse is blown. However, to makeit still more certain that this can be seen through the mica disc, Iprefer to construct the rod 9 of glass or other easily shatteredmaterial and to color the rod in some prominent color which will appearas a. colored line across the mica disc. When glass or similar 59material is used in the construction of the rod PLUG 1929. Serial No.380,828.

the heat from the fusing of the metal strip causes the rod to beshattered, thus when the fuse is blown the colored line will havedisappeared. v a

The foregoing will show that I have succeeded in providing extremelysimple and inexpensive means for positively indicating the condition ofa fuse plug. By employing variously colored rods the capacity of thefuses may be indicated. i 60 'Having described my invention and itsobject, what I claim as new and wish to protect by Letters Patent is:

1. In a fuse plug, an insulating body member having an interior recesscovered with transparent material, a metal ferrule for securing the plugin a socket attached on the outside of said body member, a metal contactsecured in the bottom of said body member, a fusible metal stripcontained in the recess and connecting the ferrule with the contact, anda rod over which the fusible metal passes suspended in seats formeddiametrically opposite each other at the top of the recess.

2. In a fuse plug, an insulating body member having an interior recesscovered with transparent material, a metal ferrule for securing the plugin a socket attached on the outside of said body member, a metal contactsecured in the bottom of said body member, a fusible metal. stripcontained in the recess and connecting the ferrule with the contact, asupporting rod over which the fusible metal passes inserted in two seatsformed at the top of the recess substantially opposite each other, andthat part of the fusible metal which passes over the said rod decreasedin size.

3. In a ,fuse plug, an insulating body member having an interior recesscovered with transparent material, a metal ferrule secured on theoutside of said body member, a metal contact secured in the bottom ofthe body member, a fusible metal strip contained in the recess andconnecting the ferrule with the contact, and a supporting means made ofglass over which the fusible metal passes secured across the top of therecess.

4. In a fuse plug, an insulating body member having an interior recesscovered with transparent material, a metal ferrule secured on theoutside of said body member, a metal contact secured in the bottom ofthe body member, a fusible metal strip contained in the 5 recess andconnecting the ferrule With the contact, and a colored and easilyshattered supporting member over Which the fusible metal passes securednear the top of the recess. o 10 5. In a fuse plug, an insulating bodymember having an interior'recess covered with transparent material, ametal ferrule secured on the outside of said body member, a metalcontact secured in the bottom of the body member, a fusible metal stripcontained in the recess and connecting the ferrule with the contact, andeasily shattered supporting rod over Which thefusible metal passessecured across the top of the recess, and said rod colg0 ored toindicate the capacity of the fuse.

LOUIS LUDW'IG,

